PERSONAL HEALTH

By Jane E. Brody

Published: April 17, 1985

IT'S not easy to be a well-informed menopausal woman

these days. Keeping up with the

latest medical information and recommendations about estrogen replacement therapy or E.R.T., a popular treatment for the symptoms of menopause, is a challenge even for experts in the field. Among those who stay on top of current research, there is widespread controversy over its interpretation.

From the early 1960's to the mid- 1970's, estrogens to replace the hormone loss that occurs naturally at menopause were widely touted in this country as the route to perpetual femininity and prolonged youthfulness. The message was sweet news to millions of American women who suffered debilitating menopausal symptoms or dreaded the ravages of age.

About half of American women at or past menopausal ages were taking estrogen supplements when the bad news came in 1975, linking E.R.T. to a significantly increased risk of developing cancer of the endometrium, the lining of the uterus. Within a year or two, the use of menopausal hormones had declined precipitously. Now, however, the pendulum seems to be swinging back in favor of hormone use, as medical researchers devise safer ways to administer the hormones and identify important benefits associated with them.

Although most women who receive E.R.T. use it for a year or so to temper the symptoms of menopause, such as hot flashes, night sweats and vaginal dryness, probably its most important use is in helping to prevent bone loss, which can lead to osteoporosis (fragile bones) and, almost inevitably, to fractures. When taken over many years, starting within the first year or so after menopause, estrogens have been shown to reduce the rapid loss of bone that commonly afflicts postmenopausal women. Those on long-term hormone replacement are 50 to 60 percent less likely to suffer fractures of the hip and forearm than women who do not take the hormones, according to Dr. Jean Coope, author of ''The Menopause'' (Arco, 1984, $12.95).

When and if estrogen therapy is stopped, bone loss will resume, possibly at a slower rate, since the rate of postmenopausal bone loss naturally slows some years after menopause. Estrogen replacement is considered especially important in combatting bone loss in women who have had their ovaries removed several years before natural menopause.

Although doctors are still concerned about hormonally induced cancers, they point out that many more women die from the complications of fractures caused by osteoporosis than from endometrial cancer. Dr. David L. Oshin of Mount Sinai Medical Center in New York, for example, says that each year osteoporosis indirectly causes the deaths of 15,000 to 30,000 women, or five to 10 times the number of deaths from endometrial cancer. The women whose deaths are related to osteoporosis tend to be considerably older than the women whose deaths are cancer-related. Still, the tradeoff is worth considering.

Among women who use E.R.T. only a few years, the vast majority, 99 percent, do not develop endometrial cancer. Among those who use the therapy for five years or longer, however, the cancer incidence is 11 percent. If a woman has an endometrial examination before starting the therapy and if the examination is repeated every year or so, it should be possible to determine whether she faces a cancer risk, which would make any hormone use inadvisable. A woman who has had a hysterectomy, in which the uterus has been removed, obviously faces no risk of endometrial cancer.

Recent studies suggest that the cancer risk may be further reduced by new methods of administering E.R.T. that are safer than the methods used in the past. Not only are lower doses of estrogen now known to be effective in controlling menopausal symptoms than the doses originally prescribed, but the latest evidence indicates that combination hormone therapy - estrogen along with progestin - greatly reduces and possibly eliminates the risk of E.R.T.-caused cancer.

In a woman who is still having normal menstrual periods, estrogen released by the ovaries each month builds up the endometrium. Following ovulation, the hormone progesterone is released in addition to estrogen. When progesterone release stops toward the end of each menstrual cycle, endometrial tissue is sloughed off, resulting in menstrual bleeding. As long as this monthly tissue loss occurs, the risk of developing endometrial cancer is practically nil. That is why the addition of a synthetic form of progesterone, progestin, to the E.R.T. regimen can minimize the effects of estrogen on uterine tissue.

The most widely recommended regimen calls for using estrogen in the lowest effective dose three weeks each month. During the last 10 days of this therapy, progestin is added. Then both hormones are stopped; uterine bleeding, similar to that of a menstrual period, may occur. According to Dr. Winnifred Berg Cutler, Dr. Celso-Ramon Garcia and Dr. David A. Edwards, authors of ''Menopause'' (W. W. Norton, 1983, $15): ''If no menstrual period follows the hormone- free days, you can assume that your endometrium is okay - that is, it was not overstimulated by the estrogen.'' At this point, they suggest that a woman might safely eliminate the progestin.